1. Field of the Invention
The present invention relates to an inkjet head in which a drive circuit member is mounted on a laminated-type inkjet head member, and an image forming apparatus having the same.
2. Description of the Related Art
In the related art, as a type of printer, there is known an inkjet printer that prints on a medium such as a paper sheet by moving an inkjet head, which discharges a liquid such as ink, relative to the medium.
In order to selectively drive nozzles that discharge droplets in inkjet heads mounted in inkjet printers, a drive circuit member including a drive integrated circuit (IC) is used. The drive circuit member is connected to an electromechanical transducer such as a piezoelectric element or a heater which generates force to discharge the liquid. As for techniques for mounting the drive circuit member, there is some known techniques, a flip chip bonding technique, a wire bonding technique, and so on.
As such an inkjet head, the following structure is known. The structure includes a pressure generating chamber communicating with a nozzle; a vibrating plate forming a part of the pressure generating chamber; a piezoelectric element which is arranged in the vibrating plate, particularly in the surface opposing the pressure generating chamber and which generates a change in the internal pressure of the pressure generating chamber; and a drive circuit member having a drive element to drive the piezoelectric element. In the structure, the drive circuit member is bonded to a terminal provided in the piezoelectric element using the flip chip bonding technique, and is mounted on an ink tank plate as a fluid path forming plate. Furthermore, a liquid supply plate as a protection plate is bonded to the ink tank plate (for example, refer to Japanese Patent Application Laid-open No. 2006-116767).
There is also known an inkjet head in which the drive circuit member is mounted through a wire connector after the liquid supply plate is bonded to the ink tank plate (for example, refer to Japanese Patent Application Laid-open No. 2009-267428).
However, since the sealing material to be coated on the ink tank plate to protect a connector portion of the drive circuit member is apt to wetly spread, it wetly spreads on the ink tank plate. Therefore, in a case where a liquid supply plate as a protection plate is bonded to the ink tank plate as in the inkjet head disclosed in Japanese Patent Application Laid-open No. 2009-267428, it is necessary to avoid an area where the sealing material wetly spreads in order to obtain an excellent bonding state without any void. This results in the inkjet head having a large size. Since the area where no wet-spreading of the sealing material appears is not supported by the liquid supply plate, the inkjet head has a weak structural strength there and hence is susceptible to deformation caused by an external force, resulting in the reliability being not guaranteed.
Similarly, in the inkjet head disclosed in Japanese Patent Application Laid-open No. 2009-267428, in a case where another member is additionally stacked on the liquid supply plate where the drive circuit member is mounted, the member must be stacked avoiding the area where the sealing material wetly spreads. This causes a large-sized head and reduces a structural strength.
In addition, since it is necessary to perform mounting, typically, at a high temperature of 150° C. to 300° C. in order to increase the strength of the electrical connection portion of the drive circuit member, an adhesive used to bond other members may be degraded to generate bonding errors, or a material which can be used as a constituent member is problematically limited to those having heat resistance.